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Planting cover crops with a purpose

By Janet Kubat Willette

Date Modified: 10/14/2013 3:26 PM

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ST. CHARLES, Minn. — Bruce Gilbeck hopes the multi-species cover crop mix growing on 89 acres north of St. Charles will break the cycle of corn rootworm he's been fighting.

Gilbeck, of St. Charles, planted 284 acres of prevented plant land to a mix of Sunn hemp, sorghum-Sudan grass, radish and oats.

He selected the cocktail of seeds based on what they are supposed to bring to the soil. The radish was chosen to break up compaction and scavenge nitrogen. The sorghum-Sudan grass should build organic matter and create plenty of crop residue. The Sunn hemp is a nitrogen source and the oats provide quick growth.

The seed was purchased from Midwest Bio-Ag in Utica.

The mixture hits both the warm and cool season grass and warm and cool season broadleaf categories, said Sue Glende, district conservationist for the Natural Resources Conservation Service in Winona County.

Gilbeck prepared the fields for planting by first spraying glyphosate and 2-4-D to kill weeds. Two weeks later, he returned to work the field with a field cultivator. The fields were planted immediately after tillage to minimize moisture loss.

The fields were drill seeded the last week of July into early August, Gilbeck said.

A field visited last week was planted Aug. 1 and already the sorghum-Sudan grass was nearly five feet tall in spots and the Sunn hemp was starting to blossom.

The field was fertilized with hog manure in preparation for planting a corn crop, but when excessive rainfall prevented him from planting corn, Gilbeck decided to try something different.

He wanted to hold the fertilizer he had already applied, and perhaps add some back. He expects the Sunn hemp to add 50 pounds to 60 pounds of nitrogen per acre.

"I didn't think the radishes would be quite as aggressive," Gilbeck said as he surveyed the field.

The mixture was planted at 25 pounds to the acre. It was dry when he planted and he knew good soil to seed contact would be essential to good growth.

He's pleased to see the growth and is optimistic corn rootworm won't be a problem in the field next year, unless it has extended diapause. The field visited has a long history of corn rootworm. Gilbeck uses a rootworm corn and has applied insecticide to keep the pest at bay for the past six or eight years.

Next spring, Gilbeck plans to plant the field to corn. He will plant it all to the same variety and compare yields against a neighboring soybean field. He will plant a non-rootworm corn and only apply soil insecticide.

"If this outproduces where the beans are . . ." Gilbeck said.

"You're going to be sold," Glende said.

"Big time," Gilbeck said.

Gilbeck's crop is generating questions. One guy stopped him when he was planting to ask questions. Others have asked questions after driving past the field of deep green.

The cover crops planted in the county are generating calls to the NRCS office, too, Glende said. Environmental Quality Incentive Program funds are offered to try cover crops. This year, 3,600 acres of cover crops were planted in Winona County using EQIP cost-share.

The cost-share covers the seed cost, Gilbeck said.

"This was a lot more money to plant than oats," he said. "You're investing in your future by doing this."

Glende encourages producers who harvest corn silage or peas to plant a cover crop.

It is a learning process when planting a cover crop, Gilbeck said, but there are so many benefits. The erosion control itself is a huge positive.

"It just pains me to see it (topsoil) leave," he said.

His cover crops near St. Charles won't be harvested in the fall. Gilbeck said that would remove all the biomass and defeat the purpose of why he planted the multi-species mixture.

Instead, he will chop the cover crops after a good hard frost and leave it lay overwinter. In the spring, he will do one pass with a field cultivator and plant.

The idea is to work it shallow, two to three inches deep, Glende said, to allow for good soil to seed contact.

Gilbeck raises corn, soybeans, hay and pumpkins. He's moved to more corn-on-corn over the past three to four years. He also works for Crop Production Services, calling on retailers in southeast Minnesota.